Refactors generate_buildtime_environment_variables() to use an associative
array (dictionary) approach instead of sequential push() calls. This prevents
duplicate variable declarations in the buildtime.env file.
**Problem:**
After adding nixpacks plan variables to buildtime.env, the same variable
could appear twice in the file:
- Once from nixpacks plan (e.g., NIXPACKS_NODE_VERSION='22')
- Once from user-defined variables (e.g., NIXPACKS_NODE_VERSION="22")
This caused shell errors and undefined behavior during Docker builds.
**Root Cause:**
The push() method adds items sequentially without checking for duplicate
keys. When a variable existed in both nixpacks plan AND user-defined vars,
both would be written to the file.
**Solution:**
- Use associative array ($envs_dict) for automatic deduplication
- Establish clear override precedence:
1. Nixpacks plan variables (lowest priority)
2. COOLIFY_* variables (medium priority)
3. SERVICE_* variables (medium priority)
4. User-defined variables (highest priority - can override everything)
- Convert to collection format at the end
- Add debug logging when user variables override plan variables
**Benefits:**
- Automatic deduplication (array keys are unique by nature)
- User variables properly override nixpacks plan values
- Clear, explicit precedence order
- No breaking changes to existing functionality
Fixes#7114🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude <noreply@anthropic.com>
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